1. Field of the Invention
The present invention relates to irrigation sprinklers and, more particularly, to a swivelling fan-jet sprinkler of the type which has a slowly swivelling horizontal nozzle cylinder with a row of jet nozzles arranged in a fantail pattern, including means for adjusting the action of the sprinkler for the coarse sprinkling of a large area or the gentler spraying of a smaller area.
2. Description of the Prior Art
Swivelling sprinklers of the above-mentioned type are known from the prior art. They are being used for the watering of lawns as well as the irrigation of vegetable and flower beds, having the advantageous capability of covering an area of square or rectangular outline. However, the size of the drops and the intensity of the water jets which are optimal for one application are generally not optimal for the other. Lawns, for example, are much less sensitive to the size of the water drops than most vegetables and flowers, and they will tolerate relatively large drops without damage. The intensity and size of the water jets, on the other hand, determine the length of the trajectory of the water drops and, consequently, the size of the area covered. At the same water pressure, large drops have a longer trajectory than small drops.
It has therefore already been suggested to provide such a swivelling fan-jet sprinkler with a means for adjusting the water jets at the nozzle cylinder. Such a device is disclosed in the German Pat. No. 19 26 735 which describes a sprinkler with an angularly adjustable control sleeve arranged on the inside of its nozzle cylinder and held in place by friction. The angular position of the control sleeve determines the degree to which the openings of the nozzle bores are obstructed and the intensity of the water jets is reduced. The result is a corresponding reduction in the size of the area covered. It includes the possibility of atomizing the water jets, in which case the droplet trajectory is very much shortened. It has been found, however, that atomization of the water is not necessary, even for the most delicate of cultivated plants.